:root {
  --primary-color: #1a237e;
  --secondary-color: #3949ab;
  --accent-color: #ffc107;
  --background-color: #f5f5f5;
  --text-color: #212121;
  --light-text: #ffffff;
}

body {
  font-family: 'Roboto', sans-serif;
  background-color: var(--background-color);
  color: var(--text-color);
}

h1, h2, h3, h4, h5, h6 {
  font-family: 'Playfair Display', serif;
}

.navbar {
  background-color: var(--primary-color);
  box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.navbar-brand, .nav-link {
  color: var(--light-text) !important;
  font-weight: 600;
  transition: color 0.3s ease;
}

.nav-link:hover {
  color: var(--accent-color) !important;
}

.hero {
  background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
  color: var(--light-text);
  padding: 8rem 0;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  /* // removed external Unsplash background image */
  background: radial-gradient(circle at top left, rgba(255, 255, 255, 0.15), transparent 55%);
  opacity: 0.2;
  z-index: 0;
}

.hero-content {
  position: relative;
  z-index: 1;
}

.search-container {
  max-width: 600px;
  margin: 0 auto;
}

.feature-card {
  transition: all 0.3s ease-in-out;
  border: none;
  border-radius: 10px;
  overflow: hidden;
  box-shadow: 0 5px 15px rgba(0,0,0,0.1);
  background: white;
  height: 100%;
}

.feature-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 25px rgba(0,0,0,0.2);
}

.feature-icon {
  font-size: 2.5rem;
  color: var(--accent-color);
  margin-bottom: 1rem;
}

.btn-primary {
  background-color: var(--accent-color);
  border-color: var(--accent-color);
  color: var(--primary-color);
  font-weight: bold;
  transition: all 0.3s ease;
}

.btn-primary:hover {
  background-color: #e0a800;
  border-color: #e0a800;
  transform: translateY(-2px);
  box-shadow: 0 5px 10px rgba(0,0,0,0.2);
}

footer {
  background-color: var(--primary-color);
  color: var(--light-text);
}

.social-icons a {
  color: var(--light-text);
  font-size: 1.5rem;
  margin-right: 1rem;
  transition: color 0.3s ease;
}

.social-icons a:hover {
  color: var(--accent-color);
}

.logo-text {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--light-text);
}

.logo-subtitle {
  font-size: 1.2rem;
  opacity: 0.8;
}

#particles-js {
  position: absolute;
  width: 100%;
  height: 100%;
  top: 0;
  left: 0;
  z-index: 0;
}

.definition-section {
  background-color: #ffffff;
  border-radius: 10px;
  padding: 2rem;
  box-shadow: 0 5px 15px rgba(0,0,0,0.1);
  margin-bottom: 3rem;
}

.key-features {
  background-color: #e8eaf6;
  padding: 4rem 0;
}

.category-card {
  background-color: #fff;
  border-radius: 10px;
  padding: 1.5rem;
  margin-bottom: 1.5rem;
  transition: all 0.3s ease;
  box-shadow: 0 5px 15px rgba(0,0,0,0.1);
}

.category-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 25px rgba(0,0,0,0.2);
}

.category-icon {
  font-size: 2rem;
  margin-bottom: 1rem;
  color: var(--accent-color);
}

.feature-list {
  list-style-type: none;
  padding-left: 0;
}

.feature-list li {
  margin-bottom: 1rem;
  padding-left: 2rem;
  position: relative;
}

.feature-list li::before {
  content: "\f00c";
  font-family: "Font Awesome 5 Free";
  font-weight: 900;
  position: absolute;
  left: 0;
  top: 0;
  color: var(--accent-color);
}

#microphone-button {
  background: none;
  border: none;
  color: var(--accent-color);
  font-size: 1.5rem;
  cursor: pointer;
  transition: color 0.3s ease;
}

#microphone-button:hover {
  color: var(--primary-color);
}

.search-result {
  background-color: #fff;
  padding: 1rem;
  border-radius: 10px;
  box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.search-results-list {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.omni-category-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(110px, 1fr));
  gap: 0.5rem;
  max-height: 360px;
  overflow-y: auto;
  padding: 0.25rem;
}

.omni-category-grid .omni-category-item {
  font-size: 0.8rem;
  padding: 0.45rem 0.75rem;
  border-radius: 999px;
  border: 1px solid rgba(0, 0, 0, 0.06);
  background-color: #ffffff;
  display: flex;
  align-items: center;
  justify-content: space-between;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.04);
  transition: all 0.18s ease-in-out;
}

.omni-category-grid .omni-category-item .badge {
  font-size: 0.7rem;
}

.omni-category-grid .omni-category-item:hover {
  background-color: #f3f4ff;
  transform: translateY(-1px);
  box-shadow: 0 3px 8px rgba(0, 0, 0, 0.08);
}

.omni-category-grid .omni-category-item.active {
  background-color: #1a237e;
  color: #ffffff;
  border-color: #1a237e;
}

.omni-category-grid .omni-category-item.active .badge {
  background-color: rgba(255, 255, 255, 0.9);
  color: #1a237e;
}

.omni-article-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 0.75rem;
}

.omni-article-grid .omni-category-article {
  font-size: 0.85rem;
  padding: 0.7rem 0.8rem;
  border-radius: 0.75rem;
  border: 1px solid rgba(0, 0, 0, 0.06);
  background-color: #ffffff;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.06);
  transition: all 0.18s ease-in-out;
  min-height: 72px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.omni-article-grid .omni-category-article h6 {
  font-size: 0.9rem;
}

.omni-article-grid .omni-category-article small {
  font-size: 0.75rem;
}

.omni-article-grid .omni-category-article:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.14);
  border-color: rgba(26, 35, 126, 0.3);
}